The image from lexjuris site
is not very impressive. It shows the Coat of Arms of the capital
of Puerto Ricoon a white field. On the homepage of San Juan <www.sanjuan.org>
there is a small Coat of Arms, a slightly bigger Coat of Arms and
... no flag; there are long descriptions of Coat of Arms and
flag(s?). I gather that there has been a 'najanjito' flag with
the Coat of Arms and that there is a close connection between the
Coat of Arms of Puerto Rico and San Juan. San Juan is on the
north coast of Puerto Rico; the oldest part of the city was built
on an island in a large bay which has a narrow entrance,
connected with mainland by a causeway and bridges; there is the
School of Tropical Medicine of the University of Puerto Rico. The
site was first visited (1508) by Ponce de le'on who made a
settlement (Caparra) 1509 on the mainland; in 1511 Caparra
abandoned and site on the island settled; fortifications begun
1533, El Morro castle built 1539-84; attacked by Drake and
Hawkins 1595; held by the British under Lord Clifford for a short
time 1598; sacked by the Dutch 1625; attacked again
unsuccessfully by British 1797; occupied by Americans 1898. There
are 437,745 Sanjuaneros. Jarig Bakker , 5 Febuary 2000

The sanjuan.org
site says: "Shield of the City of San Juan. The shield
of the City of San Juan is very similar to that of Puerto Rico,
both having as the principal charge the Lamb of God or Paschal
Lamb, which represents Jesus Christ and St. John the Baptist. It
was natural to place the Paschal Lamb on the shield of the
island, which was originally called Island of St. John the
Baptist, and on that of the capital. With the passage of time,
"San Juan" came to be the name of the capital and
"Puerto Rico" that of the island. St. John the Baptist
is the patron saint of the city. The shield of San Juan is blue.
The lamb is shown standing on a rock. This lamb represents, in
the first place, Jesus Christ the Redeemer. It is for this reason
that its head has a halo which carries the emblem of the cross.
The flag carried by the lamb, silver or white with a red cross,
represents the sacrifice of Christ on the cross and also His
triumph, in the resurrection, over sin and death. The lamb
moreover represents St. John the Baptist, prescursor of the
Savior, who pointed out Christ saying: "Behold the Lamb of
God, who takes away the sins of the world." The rock on
which the lamb stands has a double significance. In the first
place, it represents Mount Zion, symbol of the city of Jerusalem
and the Church. The stream that flows from it represents the
rivers of paradise and the sacraments, particularly baptism. In
the second place, the rock placed on the waves of water
represents the islet of San Juan, location of our capital. The
mural crown is the emblem with which are adorned the shields of
villages, towns, and cities, principally those that are or have
been fortified or surrounded by walls, like San Juan. This shield
represents a history of constancy and heroism. In the year 1799,
King Charles IV of Spain, to reward the valor and fidelity shown
by the sons of Puerto Rico on the occasion of the last English
attack on San Juan (1797), granted the capital the privilege of
surrounding its arms with the following motto: For her constancy,
love, and fidelity, this city is very noble and loyal. For the
450th anniversary of the City of San Juan, and with the
assistance of the Institute for Puerto Rican Culture, in 1971 the
Municipal Assembly decided to reform the shield as well as the
seal and official flag of the city. The ordinance provided that
"the arms of the capital be purified of the elements that
have been attached to it without historical or heraldic
justification, that certain details be added which are
undoubtedly merited, and that they se le añadan ciertos detalles
de que indebidamente carece, and that they be given a character
more in keeping with the simplicity and precision that
characterize both ancient as well as contemporary heraldry."
In this year the flag was changed to a "white rectangular
field with the shield of arms on the center." The first flag
of the capital city was officially adopted on March 8, 1948, by
the Municipal Assembly. It was an entirely orange field, on the
center of which were depicted the arms of the city. The color
then given to the flag was based on a text of Don Diego de Torres
Vargas, taken form his description of the city and island of
Puerto Rico in the year 1647, which read: "Shield of arms
granted to Puerto Rico by the Catholic Kings in the year 1511, an
inhabitant named Pedro Moreno being the Procurator. They are: a
white lamb with its red pennant, upon a book, and all on a green
island, which is that of Puerto Rico, and on the sides an F and
and I, which represent Fernando and Isabel, the Catholic Kings
who granted them, and today remain on the royal standard, which
is an orange damask, with which the city was won."
Comment: The lamb resting on the book remains, I believe, the
arms of the Commonwealth of Puerto Rico.Joe McMillan , 6 Febuary 2000

Here's what's said at lexjuris site
It's pretty much a condensed version of what's at the sanjuan.org
site.
SHIELD
The shield of the City of San Juan is very similar to that of
Puerto Rico, both having as the principal charge the Lamb of God
or Paschal Lamb, which represents Jesus Christ and St. John the
Baptist. The shield represents a complete history of constancy
and heroism.
FLAG
On March 8, 1948, the Municipal Assembly of San Juan officially
adopted, as the flag of the capital of Puerto Rico, a white
field, in the center of which is the coat of arms of the city.
[Note: This conflicts with the sanjuan.org site, which attributes
the white flag to a later date, as well as to the language of the
very next paragraph:] . The color of the flag is based on a text
of Canon Don Diego de Torres Vargas, taken from his
"Description of the City and Island of Puerto Rico"
(1647), Joe McMillan , 6 Febuary 2000

This is the one appearing in pueblos-de-puertorico and the one
seen actually flying in the Capital City.Blas Delgado, 7 March 2000

It is interesting to me to see that the emblem on the flag for
San Juan. That ram is holding a St. George's flag, which seems to
me to represent England.
Is there a story about this emblem?steve stringfellow, 7 March 2000

The Paschal lamb (not ram), or Lamb of God, has been an
iconographic symbol of St. John the Baptist since very early
times. Both Christ and St. John as well as the Lamb are
frequently depicted carrying a white flag with a red cross on it.
The association with St. George is, I believe, derivative if not
coincidental. The blazon of the San Juan arms actually refers to
the banner as that of St. John.Joe McMillan, 7 March 2000

St George for England is not that old - crusades time but the
order of St. John has the silver cross with the red background.
That might be related to the first silver processional cross
about 300 AD which had red wool tied to it to represent the blood
of JesusHugh Watkins , 11 March 2000

This is the current shield as depicted in several official ads
and in the actual flag flowing at the Hiram Bithorn Stadium
gates. They are not new, the flag's been flowing since several
years by now.Blas Delgado Ortiz, 11 November 2004

It has reached my hands in the form of photocopies some very
interesting and important information about the understanding of
the Puerto Rican Arms. Pitifully, the source is nowhere
identified but appears to be sections of a chapter of a somewhat
recent publication:
San Juan City Coat of Arms - The city of San Juan started using a
shield by the end of the XVI or the beginning of the XVII century
in which the Pascal Lamb (named sometimes the San Juan Lamb)
appeared as the main image. The shield differed in many ways to
the Puerto Rican Arms: its background was blue instead of green;
it has no orle or bordure; the lamb was standing in it over the
book and this placed over a green isle rising from the sea; and,
neither the F and initials, uncrowned, the ox-yoke nor the arrows
appeared in or outside the shield. The differences may have been
the result of either giving the capital city its own shield,
dissimilar to the Island's, or an unfruitful effort in
reproducing by way of memory the original shield of Puerto Rico.
We have to remember that the city of San Juan was once called
Puerto Rico of San Juan Bautista.
As time went by, the differences between both shields were being
accentuated. In the XVIII century: the book was concealed from
the San Juan shield; the isle presents a bay or a spring flowing
out, a symbol of baptism; the motto "Joannes est nomen
eius" is added; and, the F and I (Latin I) initials are
placed in or outside the blazon field, sometimes joined by the
ox-yoke and the sheaf of arrows.
The city of San Juan will keep using the shield during the XVIII
and XIX centuries, and the same shield will be used officially
since the beginning of the XIX century as the Arms of Puerto
Rico. It was not until 1899, following the war between Spain and
the United States and the occupation of the Island by the latter,
that several versions for a Puerto Rican Arms were presented to
the Military Governor, Brigadier General Geo W. Davis, as means
to appeal to the resurging idea to restore the primitive shield
of the Island. [Unfortunately, the page ends with an unfinished
sentence stating that one of the designs, from an unknown author,
merged the original San Juan City shield with. probably the XVIII
century one?]Blas Delgado Ortiz, 3 Febuary 2004

From <www.linktopr.com>:
The origin of this Coat of Arms is uncertain, we only know that
it has been used for several centuries and that through time its
design has undergone several modifications, none of them of great
importance. The shield of the City of San Juan is very similar to
the one of Puerto Rico. Both use as the main figure the Lamb of
God or Paschal Lamb, which represents Jesus Christ and San Juan
Baptist. It was natural to use the Paschal Lamb in the shield of
the Island - originally called Island of San Juan Baptist - and
in the Capital's shield. With time, San Juan became the name of
the Capital and Puerto Rico the Island's name. San Juan Baptist
is also the Patron Saint of the City. The shield of San Juan is
blue. The lamb appears standing on a rock. This lamb represents,
first, Jesus Christ Redeemer, which is the reason it has an
aureole with a cross above its head. The silver-plated or white
flag with a red cross, carried by the lamb, represents Christ's
sacrifice at the cross and his resurrection and triumph over sin
and death. Additionally, the lamb represents San Juan Baptist,
precursor of the Savoir because San Juan Baptist was the one who
signaled to Christ saying: "Here is the Savoir, who cleanses
the world of sin". The rock on which the Lamb stands has a
double meaning. It represents: firstly, Mount Sion, symbol of the
holy city of Jerusalem and the Church with the spring that flows
representing the rivers of Paradise and the Sacraments,
particularly baptism; secondly, it shows the rock on waves of
water representing the isle on which our capital, San Juan,
stands. The mural crown is the emblem adorning the shields of
towns, villas and cities, mainly those that are or were
fortified, surrounded by walls like San Juan. This shield
represents a history of constancy and valor. In the year 1799
King Charles IV of Spain, in appreciation of the value and
fidelity shown by the citizens of Puerto Rico on the occasion of
an English attack upon San Juan in 1797, granted the city the
privilege to trim the Coat of Arms with the following motto:
"POR SU CONSTANCIA, AMOR Y FIDELIDAD, ES MUY NOBLE Y MUY
LEAL ESTA CIUDAD" (For constancy, love and fidelity, this
city is very noble and very loyal). Nelson Román, 16 July 2004

I mentioned some photocopies that I saw describing the San
Juan's shield. These belong to the softbound book "Los Símbolos
Oficiales de Puerto Rico", by Editorial Cordillera.
Here is the San Juan City Coat of Arms for the XIX Century as
painted by José Campeche, one of our most prestigious painters
of that time. A slight version of it can be seen in Manuel
Gabino's recent collaboration about the San Juan Flag
at 10th Central-American and Caribbean Games, held in that
city in 1966. Most porbably, that flag was hastily made for the
games.Blas Delgado Ortiz, 1 January 2005

I am reporting about the flag of San Juan as hoisted during
the "X Juegos Deportivos Centroamericanos y del
Caribe" (´Tenth Central-American and Caribbean Games) in
1966. The work is all in Spanish, so that the translation (by
myself) is unofficial. The images are in black and white.
The photo of the San Juan
flag appears in the page 13 of the volume 1. The foot reads:
"El compositor Noel Estrada, funcionario de la Secretaría
de Estado y autor de la canción 'En Mi Viejo San Juan' iza la
bandera de la Capital mientras veinte mil voces cantan su
coposición" [Song-writer Noel Estrada, officer of the State
Department and writer of the song 'En Mi Viejo San Juan' (In my
old San Juan), hoists the Capital's flag while twenty thousand
voices sing his song].
The photo, a very good image, depicts the flag all but white. The
flag seems to be blue (?) instead. The San Juan arms over all the
center within an oval, perhaps red or orange or green (compared
to the other photos). The coat of arms is in an old (?) version;
it is a white oval ring bearing the motto: "es muy noble y
muy leal es[ta ciudad por] su constacia, amor y fidelidad",
in black (?) capital letters. The ring in turn surrounds the lamb
looking towards the letter "I" (then to the fly). Above
the lamb, following the upper inner edge of the oval ring, there
is the inscription: "joannes [est nom]en ejus" in
capital letters. The field appears over a mantling, that in turn,
is over a garland. The whole as I said before is within an oval.
The flag has a fringe also. Source: "Memoria de los Décimos Juegos
Deportivos Centroamericos y del Caribe" Administración de
Parques y Recreo Públicos del Estado Libre Asociado de Puerto
Rico, 1966. Two volumes. In the cover: A photo of the Games flag.
Emblem of the Comité Olímpico Puertorriqueño (COPR). Index.
Official Puerto-Rican coat of arms.Juan Manuel Gabino Villascán, 29 December 2004